Outbreak of toxoplasmosis in a flock of domestic chickens (Gallus gallus domesticus) and guinea fowl (Numida meleagris)

Genetic diversity of Toxoplasma gondii isolates from birds in the world: A systematic review

Toxoplasma gondii (T. gondii) is one of the most important foodborne pathogens that infects a large number of vertebrate species and has a cosmopolitan distribution. Birds as intermediate hosts are very important in the life cycle of T. gondii and they can be a main source of infection for humans and felids, as well as other animals. Most species of birds feed from the ground and are the best indicator for soil contamination with T. gondii oocysts. Hence, T. gondii strains isolated from birds can represent different genotypes circulating in the environment and their main predators and consumers. The recent systematic review tries to represent the population structure of T. gondii in birds around the world. Six English language databases were searched from 1990 to 2020 to find the related studies and overall, 1275 isolates of T. gondii were separated from the analyzed samples in birds. The results of our study revealed that atypical genotypes were predominant (58.8%, 750 out of 1275). Types II, III, and I had less frequency with prevalence rates of 23.4%, 13.8%, and 2%, respectively. No isolates of Type I were reported from Africa. Summarizing ToxoDB genotypes circulating in birds around the world manifested that ToxoDB #2 was the most common (101/875), followed by ToxoDB #1 (80/875), and #3 (63/875). Totally, the results of our review represented the high genetic diversity of T. gondii with circulating non-clonal strains in birds from South and North America, while clonal parasites with low genetic diversity were predominant in Europe, Asia, and Africa.

First report on the isolation and genotyping of Toxoplasma gondii strains from free-range chickens in the state of Mato Grosso, Midwestern Brazil

In the present study, 51 strains of Toxoplasma gondii (T. gondii) were isolated from free-range chickens in the state of Mato Grosso, Midwestern Brazil, upon conducting bioassays in mice, and genotyped them using PCR-restriction fragment length polymorphism (PCR-RFLP) and 11 markers, including SAG1, SAG2 (5'3'SAG2 and alt. SAG2), SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, Apico, and CS3. Fifty isolates were completely genotyped revealing 17 genotypes of T. gondii as follows: 12 matched using ToxoDB PCR-RFLP with the previously reported genotypes, including #6 type BrI (n = 4), #8 type BrIII (n = 7), #11 type BrII (n = 3), #14 (n = 1), #19 (n = 1), #41 (n = 1), #99 (n = 1), #109 (n = 4), #116 (n = 1), #140 (n = 2), #166 (n = 9), #190 (n = 1); and five genotypes have not been described before [#313 (n = 6), #314 (n = 1), #315 (n = 1), #316 (n = 1), #317 (n = 1)]. Moreover, mixed infections were identified in five isolates (TgCkBrMT8, TgCkBrMT9, TgCkBrMT33, TgCkBrMT38, and TgCkBrMT41). Additionally, genotype #190 was reported for the first time in chickens from Brazil. Our results corroborate with previous studies on T. gondii isolates identified in chickens from Brazil, thereby confirming their diversity, a typicality, and possibility of co-infection due to different T. gondii strains present in the country.

A systematic review of Toxoplasma gondii genotypes in Gallus gallus domesticus worldwide: The focus is Brazil

Toxoplasma gondii was initially classified in three main lineages related to its virulence: Types I, II, and III. The recombination of genes during sexual cycle in felids gut led to more than 200 genotypes, found in ToxoDB database, using 11 RFLP markers. Free-range chickens are good bioindicators of soil contamination with T. gondii oocysts. In this sense, there are systematic reviews regarding data of genetic characterization of this parasite in felines and ruminants, but not in chickens heretofore, what makes this work necessary. A systematic review of the literature was performed with papers published prior to September 21, 2020. The main inclusion criteria were the presence of T. gondii genotypes, isolated strictly from free-range chickens, in experimental works. Initially, a total of 1,343 studies related to the terms were identified on databases and 30 studies were selected to be systematically reviewed. A total of 561 isolates of T. gondii from 6,356 free-range chickens were analyzed for genotyping, revealing 190 genotypes. ToxoDB #59 and #2 were the most frequent in America, #1 was the most frequent in Africa and three atypical isolates from genotype ToxoDB #9 were found in Asia. There is no data from Europe and Oceania. The majority of studies were Brazilian (16/30). A total of 68 RFLP genotypes were recognized among the 561 isolates' DNAs analyzed from the 30 studies. Some studies showed new genotypes never described before, which reinforces the idea that in some years even more new genotypes will be identified, due to gradual genetic recombination. A large number of undefined genotypes makes it necessary to perform Nested PCR technique when genotyping. Moreover, the lack of data in Continents such as Europe, Asia, and Oceania makes it necessary to perform new isolating and genotyping studies in these places.

Genetic and histopathological characterization of Toxoplasma gondii genotypes isolated from free-range chickens reared in the metropolitan region of Rio de Janeiro state, Brazil

This study aimed to genetically characterize Toxoplasma gondii isolates obtained from free-range chickens reared in the metropolitan region of the state of Rio de Janeiro, Brazil, and to evaluate the morbidity and histological changes associated with these isolates in mice. A mouse bioassay was used to isolate T. gondii from a pool of tissue samples (brain, heart, and thigh muscles) collected from 163 chickens. The 36 isolates obtained were genetically characterized by restriction fragment polymorphism (PCR-RFLP) analysis of the SAG1, 5'-3'SAG2, aSAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, Apico, and CS3 genomic regions. Seventeen atypical genotypes were identified and nine of them were reported for the first time. All identified genotypes caused clinical signs and histological changes in mice, with the majority being associated with high cumulative morbidity (65%) and severe or very severe histological changes (76%). The exclusive identification of atypical genotypes, with a predominance of new genotypes, indicates great genetic diversity of T. gondii in the region studied. In addition, the finding that all identified genotypes caused clinical signs and often severe histological changes in mice suggests potentially relevant virulence of these strains.

Epidemiologic significance of Toxoplasma gondii infections in turkeys, ducks, ratites and other wild birds: 2009-2020

Toxoplasma gondii infections are common in humans and animals worldwide. Wild and domestic avian species are important in the epidemiology of T. gondii infections because felids prey on them and excrete millions of oocysts in the environment, disseminating the infection. Herbivorous birds are also excellent sentinels of environmental contamination with T. gondii oocysts because they feed on the ground. Toxoplasma gondii infections in birds of prey reflect infections in intermediate hosts. Humans can become infected by consuming undercooked avian tissues. Here, the authors reviewed prevalence, persistence of infection, clinical disease, epidemiology and genetic diversity of T. gondii strains isolated from turkeys, geese, ducks, ratites and avian species (excluding chickens) worldwide 2009-2020. Genetic diversity of 102 T. gondii DNA samples isolated worldwide is discussed. The role of migratory birds in dissemination of T. gondii infection is discussed.

Epidemiologic significance of Toxoplasma gondii infections in chickens (Gallus domesticus): the past decade

Toxoplasma gondii infections are common in humans and animals worldwide. Domestic free-range chickens (Gallus domesticus) are excellent sentinels of environmental contamination with T. gondii oocysts because they feed on the ground. Chickens can be easily infected with T. gondii; however, clinical toxoplasmosis is rare in these hosts. Chickens are comparatively inexpensive and thus are good sentinel animals for T. gondii infections on the farms. Here, the authors reviewed prevalence, the persistence of infection, clinical disease, epidemiology and genetic diversity of T. gondii strains isolated from chickens worldwide for the past decade. Data on phenotypic and molecular characteristics of 794 viable T. gondii strains from chickens are discussed, including new data on T. gondii isolates from chickens in Brazil. This paper will be of interest to biologists, epidemiologists, veterinarians and parasitologists.

Isolation and molecular characterization of Toxoplasma gondii from placental tissues of pregnant women who received toxoplasmosis treatment during an outbreak in southern Brazil

Toxoplasma gondii is a protozoan that has great genetic diversity and is prevalent worldwide. In 2018, an outbreak of toxoplasmosis occurred in Santa Maria, Brazil, which was considered the largest outbreak ever described in the world. This paper describes the isolation and molecular characterization of Toxoplasma gondii from the placenta of two pregnant women with acute toxoplasmosis who had live births and were receiving treatment for toxoplasmosis during the outbreak. For this, placental tissue samples from two patients underwent isolation by mice bioassay, conventional PCR and genotyping using PCR-RFLP with twelve markers. Both samples were positive in isolation in mice. The isolate was lethal to mice, suggesting high virulence. In addition, the samples were positive in conventional PCR and isolates submitted to PCR-RFLP genotyping presented an atypical genotype, which had never been described before. This research contributes to the elucidation of this great outbreak in Brazil.

Seroprevalence and risk assessment of Toxoplasma gondii in Java sparrows (Lonchura oryzivora) in China

BACKGROUND

Toxoplasma gondii, an intracellular zoonotic parasite, infects all mammalian and birds. Understanding the prevalence of Toxoplasma in bird is important for evaluating the transmission of this parasite. No information about the seroprevalence of T. gondii in Java sparrows (Lonchura oryzivora) is available.

RESULTS

In this study, from 2014 to 2015, 350 serum samples from Java sparrows were collected in Beijing and Shangqiu, Henan province, and the antibodies against T. gondii were evaluated with MAT. The seroprevalence in Java sparrows was 34.29% (CI_95% 29.31-39.26). A phenomenon of seropositivity tended to increase with age were observed, but the difference is not significant. The prevalence was significant different in gender and color, which could be risk factors.

CONCLUSIONS

This study firstly reported T. gondii seroprevalence in Java sparrows, which extended the host range of T. gondii. Java sparrows may pose significant transmission medium, accelerating the spread of T. gondii diffusion.